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(-No Model.) 2 sheets -sheet 1.

0. E. SORIBNER. TESTING APPARATUS FOR MULTIPLE SWITGH BOARDS.

No. 416,808. Patented Dec. 10, 1889,

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(No Model.) A 2 Sheets-Sheet G. E. SGRIBNER.

TESTING APPARATUS FOR MULTIPLE SWITCH BOARDS.

No. 416,808. Patented Dec. 10, 1889.

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" UNITED STATES PATENT OFFICE.

CHARLES E. SCRIBNER, OF CHICAGO, ILLINOIS, Assienon 'ro THEwEsTERN ELECTRIC COMPANY, or SAME PLACE.

TESTING APPARATUS FOR MULTIPLE SWITCH-BOARDS.

SPECIFICATION forming part of Letters Patent No. 416,808,.dated December 10, 1889.

Application filed June 1, 1388-- Serial No. 275,752. (No model.) H

To aZZ whom it may concern: ing contact with the spring or lever of any Be it known that 1, CHARLES- E. SGRIBNER, switch in which the test-plug may be inserted, a citizen of the United States, residing at Chiand the spring 0, also insulated from the cago, in the county of Cook and State of Illishank. \Ve have thus in each test-plug three 55 nois, have invented a certain new and useful insulated terminals, which I preferably make Improvement in Testing Apparatus for Mulin'the form shown. lVith each of these tertiple Switch-Boards, (Case 156,) of which the minals a separate strand of a cord is confollowing is a full, clear, concise, and exact nectedh The terminal 0 is connected with description, reference being had to the acstrand 0, which leads to ground. Terminaloo 1o companying drawings, forming a part of this I) is connected with the wire I), which leads specification. throughfthe operators telephone and the My invention relates to multiple switchcontact of thebuzzer d andbatteryeto ground. board systems, and its object is to furnish Terminal at connects with strand a, which ready means for testing to determine whether leads to the same cont-act of the buzzer d and 65 a line Wanted or called for is in use. through battery 6 to ground. The spring- My invention is applicable to metallic-cirjack switch shown in Fig. 2 is of the usual cuit systems or single-circuit systems, but is 1 construction, having a spring or lever f, which more especially designed for use in mixed rests upon its normal contact g. The lever syste1ns-that is to say, systems in which sin= and contact or anvil are insulated. from the 70 2o gle telephone-circuits and metallic telephone test ring or piece It. On inserting the testcircuits are used conjointly. The telephoneplug in the spring-jack switch three separate lines may be run in the usual manner, a meconnections will be made therewiththat is tallic circuit being connected through the to say, the needle awillconnect with contact spring and contact-point of a switch on each '9, the ball lifting lever f flOnl said contact 75 of the boards and through an annunciator will form connection with said lever, while,

and back through the ring or testpiece of the terminal 0 of the test-plug will be eleceach of said switches. The single-line cirtrically connected with the test-ring 71-. Thus cuit is connected in the same manner through .the test-ring is connected through terminal 0 a spring and contact of a switch 011 each of and strand 0 to ground. The contact-point 8o the switch-boards and through an annunciis connected through the needle or terminal ator back to a test-piece or ring on each of a wit-h strand a through the buzzer and batthe switches. tery to ground, while the lever f is connected. 111 the drawings, which are illustrative of through the ball on shank Z) of theplug, my invention, Figure 1, Sheet 1, is a view of through strand I), through the operators tel- 85 3 5 two telephone-lines, one single and the other ephone to said buzzer, and through sai metallic, connected each with four different buzzer and the battery to ground. r spring-jack switches, which will be consid- In Fig. 1 the subscribers station 1 is upon, ered as upon different boards, and my testthe metallic circuit 2', which extends from said ing apparatus. Fig.2, Sheet 2, is a View station through the switches z" 1 of dif- 9o 40 showing the testing apparatus more in detail ferent boards and through an annunciator and a detailed View of a spring-jack switch loack to the test-rings of said switches, and in a line. thence back to the subscribers station 1. Like parts are indicated by similar letters The subscribers stat-ion 2 is connected by a and numerals of reference in the different single wire 7c with the central ofiice. The 5 figures. circuit of wire 7c may be traced from ground I will first describe the testing apparatus at subscribers station 2, through spring-jack in detail as shown in Fig. 2. switches 79' k 1.3 and through an annunciw The test-plug shown is provided with three ator, back through test-pieces of said spring contacts, to wit: the needle a, normally pressed jack switches and directly to ground. 5o upwardly by a spring; the metallic shank b The test-plug Z of Fig.1 is the same as the of the plug, provided with the ball for maktest-plug illustrated in Fig. 2. The spring interrupt the circuit.

jack switches t, &c., and k, &c., are p eterably of the same construction as the springjack switch illustrated in detail in Fig. 2.

The annunciators m n of the different lines may be wound so as to have a resistance of, say, fifty ohms each. The resistance of the difierent telephone-circuits, including the subscribers outfits, may be each, say, from three hundred an fifty to four hundred ohms. The resistance of the coils of the buzzer or vibrator cl may be, say, fifty ohms. The battery 6 may consist, say, of four cells of ordinary gravity-battery. The buzzer and battery are so adjusted with respect to resistance and current that the buzzer will not vibrate if the circuit closed at terminal a of the test-plug contains a resistance substantially higher than fifty oh1ns-that is to say, of substantially higher resistance than that f the annunciators m or n of the different Ines.

I will now describe the manner of testing a telephone-circuitwe will say at switch 1' of the third boardto determine whether the line i is connected or in use at any other of the boardsthat is to say, whether connection has been made with any one of the springjack switches 1', 1' or 2' of the line 2'. I will suppose, first, that the line is not busy, in which case all the spring-jack switches of the line will be closed, as shown. The operator inserts test-plug 1 into switch i and thereupon the three separate connections are made as heretofore described with respect to the testplug and spring-jack shown in Fig. 2. The test-- piece of switch 1' is thus connected with the terminal 0 of-test-plug Z, and thence through wire 0 to ground. The shank orterminal b of the test-plug is connected with the lever of switch i while the other terminal of testplug Z-that is to say the needleis connected with the contact-point, the lever being at the same time lifted from the said contact-point or anvil. The circuit of battery 6 will thus be closed through the vibrator (Z, the wire or strand a, and terminal a to the contact or anvil of switch i and thence the circuit may be traced through switch 2 and thence through annunciator m, and thence to the test-piece of switch 2' and thence through terminal c and strand 0 to ground. The resistance in the circuit thus formed between the terminal a of the test-plu g an d the ground wire 0' will be onlythat of the annunciator m, and hence the buzzer (I will be set in vibration to It will be noted, how.- ever that the circuit as just traced does not include the operators telephone 0. A derived circuit, however, is completed through the telephone 0, which may be traced as follows: beginning at battery 6 and passing I through the contact of the buzzer, thence by wire I) to the terminal I) of the test-plug, thence to the lever of switch i thence over line i through subscribers station 1 and back over the return portion of circuit 1' to the test-piece of switch 2' and thence, as before traced, by terminal 0 and strand 0 to ground. It will be observed that the resistance of the line i and the subscribers bell at station 1 would be so great that the battery 6 would not be strong enough to cause the buzzer to vibrate when closed as thus traced simply through wire i. If, however, the battery be closed through this high-resistance circuit, one listening at the telephone 0 may determine whether or not the vibrator or buzzer is being actuated. The derived circuit of battery 6 through the annunciator m, being of low resistance, will permit sufficient current to pass from the battery through the vibrator to set it in operation. Therefore, when there is no connection with any spring-jack of the line and a testis made at any one of said spring-jacks, the operator listening at the telephone will: hear the hum caused by the buzzer. Thus if he hears the hum he will know that the line is free. Suppose, however, a connection had been made at switch In this case the annunciator is disconnected as the lever of switch i is lifted from its contact-point, the lever being connected with the plug inserted at i and thence to the other telephone-line, which is connected to the line or switch 11 The two branches of the test-circuit would in this case be traced through two telephone lines of, say, four hundred ohms each, making a joint resistance of two hundred ohms, which would be so great that battery 6 would not set the buzzer in vibration, and hence no sound would be heard in the telephone 0 and the operator would know that the line was busy. Suppose, however, the connection, instead of being at switch 6 were upon the other side of the switch i as, for example, at switch 2'. Switch z" in that case would be open. The circuit, however, would be closed from the needle of the test-plug when inserted in switch 1' through the annunciator m, thence to the test-piece of spring-jack switch 2' and thence through terminal 0 and strand or wire 0 to ground. The buzzer would thus be set in vibration. This vibration, however, would cause no sound in the telephone 0, since the wire 1' would be open at switch 1;, and hence no sound would be heard in the telephone. Thus it will be seen that if the line is not in use a sound will be heard in the telephone. If the line is connected at a switch of the series of switches of the line back of the switch at which the test is made, the buzzer will not. respond, since the derived circuit through the annunciator of the line will be open, and the resistance of the other derived circuit will be so great that the battery will not be sufficient to set the buzzer in vibration. If, however, the connection is made at a switch in front of the switch at which the test is being made, the circuit will be closed through the derived circuit, which includes the annunciator of the line, and this derived circuit, having low resistance, will permit enough current to pass through the vibrator applicable to a single circuit except that in.

to set it in operation. This vibration, however, will in no wiseaffect the telephone, since the derived circuit containing the telephone is open at the switch where the' connection is madethat is to say, if the connection or break is back of the switch at which the test is made the buzzer does not respond. If the connection or break is in front of said switch,the vibrator will be set in operation; but the derived circuit containing the listening operators telephone will becase of single circuits the terminal of the testplug 0 and the strand 0 connecting the same with ground would not be necessary, since the test-pieces of the switches of single lines are connected directly to ground. Thus in testing single-line circuits the terminal 0 and branch 0 are unnecessary. It is, however, no detriment to the apparatus when applied in testing single-circuit wires, since an extra ground is provided between the test-piece of the switch at which the test is made and the ground.-

My invention admits of various modifications, which would readily suggest themselves to those skilled in the art, and I therefore do not limit myself 'to the constructions shown.

Having thus described my invent-ion, I claim as new and desire to obtain by Letters Patent- 1. The combination, with a spring jack switch consisting of the lever normally pressing against its contact-point or anvil and the insulated test ring or piece, of a testplug adapted to be inserted therein, said test-plug containing three terminals, whereby on inserting said test-plug in the spring jack switch three separate connections are made, one terminalof the plug being connected with the anvil, another with the switch-lever, and the other with-the test-piece, while the lever of the switch is at the same time lifted from its anvil, substantially as described.

2. A test-plug consisting of an insulated sleeve forming one terminal, a central needle forming another terminal, and an outer spring or coil forming a third terminal, said terminals being connected, respectively, with dif- 5. The combination, with a ground branch including a battery, of a buzzer and branch wires or circuits from the contact of said buzzer terminating in two different contacts of a plug, substantially as described.

4. The combination, with a ground branch including a battery, of a buzzer and branch.

wires or circuits from the contact of said buzzer terminating in two diiferent contacts of a plug, one of said contacts being yielding, substantially as described.

5. The combination, with a telephone-lin connected with a series of spring-jack switches and through an annunciator back through test pieces or rings of said switches, of a grounded circuit-wire containing a battery and buzzer, said circuit extending from the contact of said buzzer in derived circuit to different terminals of a test-plug or connecting device, one of said'branches containing a telephone, said connecting device being provided with a third terminal connected to ground, whereby on applying said plug or connecting device to any spring-jack switch of the line and listening at the telephone it may be determined whether any other one of the spring-jack switches of the line is open or in use.

6. The combination, with a telephone-circuit connected with two or more multiple switch-boards, of a battery, an electro-magnetic signal device, a derived circuit from said signal device, one branch of said derived circuit connecting to one portion of the said telephone-circuit, the other branch of the telephone circuit connecting with the other portion of the telephonecircuit, whereby both portions of said telephone-circuit may be tested to determine whether or not the line is in use.

In witness whereof I hereunto subscribe my name this 15th day of March, A. D. 1888.

' CHARLES E. SORIBNER.

Vitnesses:

CHAS. G. IIAWLEY," CHAS. O. WooDwoR'rH. 

